(1) Field of the Invention
The present invention relates to an aromatic polyamic acid (i.e., polyamide acid) solution composition useful as a dope for the preparation of an aromatic polyimide film, which is used for the production of a polyimide composite sheet (inclusive of a tape) comprising an aromatic polyimide film or layer and a metal film or layer, that is advantageously used for a copper clad laminate for the production of a printed circuit board used in the electronic and electric industries or is used for other electronic material, for example, a magnetic tape, according to the kind of the metal material. Furthermore, the present invention relates to an aromatic polyimide film made from this solution composition.
(2) Description of the Related Art
Polyimide composite materials, such as composite sheets, comprising an aromatic polyimide film layer and a layer of a metal material are known. These known polyimide composite sheets comprising a polyimide film layer and a layer of a metal material, however, have some problems. For example, since the aromatic polyimide constituting the aromatic polyimide film layer has a considerably larger thermal expansion coefficient than that of the metal film layer, when a composite sheet is prepared by integrally laminating the polyimide film and the metal film under heating and when the formed composite sheet is exposed to a high temperature during processing or while it is used, the composite sheet curls. Moreover, since the aromatic polyimide film is not completely satisfactory in mechanical strength, heat resistance (the heat resistance at the soldering step) or flexibility, the obtained composite sheet cannot be advantageously used on an industrial scale as an electric or electronic material.